Gun perforator



March 13, 1951 Filed -Oct. 13, 1944 R. D. ELLIOTT 2,545,024

GUN PERFORATOR 2 Shee,ts-Shee'\ l NTOR.

BY dr,

ATTORNEY.

March 13, 1951 R. D. ELLIOTT 2,545,024

GUN PERFoRAToR Filed oct. 15, 1944 2 sheets-sheet 2 INVE OR.

ATTORNEY.

Patented Mar. 113, 1951 GUN PERFORATOR Raymond D. Elliott, Long Beach, Calif., assignor, by mesne assignments, to Byron Jackson Co., Vernon, Calif., a corporation of Delaware Application October 13, 1944, Serial No. 558,581

14 Claims.

This invention relates to bullet shooting devices and has particular application to gun periorator-s for well casings although it may also be useful in other types of guns. l

A general object of the invention is to provide a simpler gun structure by changingl the usual detonating elements for exploding the powder charge.

A more specic object is to provide a method of exploding a powder charge in a gun from the muzzle end, thereby eliminating 'the necessityof providing the usual openings in the rear end of the gunfor ignition purposes.

A further object of the invention is to provide a method of discharging av projectile. from a gun perforator wherein a concussion responsive propulsive charge is detonated by the concussion from a detonating charge which is detonated in front of the projectile, and which concussion is transmitted by the projectile to the propulsive charge.

A still further object of the invention is t provide a method of' discharging a' projectile from agun perforator, characterized by detonating a concussion initiating charge in front of the projectile to force the projectile rearwardly in its gun bore, and, while the projectile is moving rearwardly, detonating a propulsiva charge rearwardly of the projectile to discharge it from the gun bore.

A kstill further object of the invention is to provide a gun perforator in which a bullet is interposed between two explosive charges in the gun bore, and in which the explosive charge 'in front 0i the bullet is detonated to force the bullet rearwardly in the gun bore .and transmit the force of the detonaton to the other explosive charge and thereby detonate the latter charge to discharge the bullet from the gun bore.

Yet another object of the invention is to, pro- .l vvide a .gun perforator as aforementioned,v whereby Fa number oi projectiles may be discharged as aforesaid, the discharge of said projectiles being accomplished by common firing means, y

Briefly, to detonate the powder charge in a gun in. accordance with the invention, I force the bullet back against Vthe powder with Vsuflicient violence to explode it. The forcing back of the bullet is preferably accomplished by firing a relatively vsmall amount of relatively powerful, fast-acting explosive in front of the bullet. In a gun perforator for similar device having a plurality of iiring chambers in a single body, the igniting explosive may be in the form of `a continuous fuse extending across the muzzles of all the chambers.

A full understanding of the invention may be part of a casing perforating' gun incorporating the invention.

Fig. 2 is a cross section taken vin the plane II-II of Fig. l;

Fig. 3 is a cross section Ataken .in the plane III- III of Fig. 1; i

Fig. -4 is a cross section showing an alternative shape of gun body to that shown in Fig. 3.;l

Fig. 5 is a fragmentary section showing a modication of the gun structure shown in Fig. 1'; this view being also a section through one of the bores of Fig. 6;

Fig, 6 is a detail side elevation showing a modifiication of the arrangement of Fig. 1; and

Figs. 7, 8 and 9 areviews similar to Fig. 5 showing alternative arrangements.

Referring first to Figs. 1 and 2, the gun therein disclosed comprisesfa solid body I0 adapted to be secured at its upper endin any desi-red manner to a cable by which it may be lowered into a well casing to be perforated. The cable may contain an insulated' electrical conductor y'I2 which is brought out of the lowervend of the cable within an adapter I I and connected by means oi a banana plug 12a lon the adapter and a jack I2b in the body I0 to another conductor It leading to an .electrical lfuse I5 Iwhich may be of standard type and functions to ijgnite .one end of a fuse-,like explosive element vI' which extends from the electrical fuse' l5 Ylongitudinally of the body Ill in a groove Il provided .for it.

As shown, thev .electrical fuse vI5 is sealed/by cement I5c within .a Afuse. tube ,I`5a which yis vheld in a pocket provided therefor in the body lill 'by a screw l5b so that the fuse is protected against wetting and physical damage during handling` of the gun and lowering it into a well.

The groove I TI, extendsl across the muzzlespf a plurality of .gun bores IS which, in the, particular form of gun shown in Fig. l, are all positioned in the same vertical plane and are vertically spaced uniformly from eac-h other. Each gun bore I 9 is completely closedat its rear end, having no opening whatsoever other than that at the muzzle enelwhich is located in each case at the groove I'I.

There is shown lin each gun bore. I9- a powder charge 2G and a bllllet 2fI, the powder charge being preferably separated from the bullet by a rmass of sealing material 12- 2 whichpreventsentry of water or other-*fluid past the bullet 12|. The sealing material V22 may be a plastic, water-,proof preparation such as rubber 0I' :plastic lsealing compound which is com-pressed between the powder charge and the bullet when the latteris placed in position.

The bullet is preferably fitted to the ,gun bore with such tightness that it retains itself'in place by friction,V although. in some .instances it may be desirable to employ loosely tting bullets `,and

maintain them in place with wadding or plastic placed in front of the ybullet as disclosed in my copending application Serial No. 527,110, led March 18, 1944, now Patent No. 2,402,153, granted June 18, 1946.

As shown in Fig. 1, the fuse-like explosive element I6 is looped into the muzzle end of each gun bore as indicated at 23. In some instances the resistance of the element I6 to bending may offer sufficient frictional engagement to retain the loops 23. However, to insure that they remain in place, each loop may be held in its associated gun bore by a flat wedge 25 of wood or plastic, which 4we'dg'e'is driven into the gun bore until its outer end is flush with the outer surface of the gun. -:-;..'Ih e explosive element I6, although being similar to a fuse in that it consists of an outer flexible; fluid-proof casing containing combustible material, differs from a conventional fuse in that the combustible material employed consists of an explosive having very fast burning characteristics so that when set off by the electrical fuse I5,

the whole element I6 explodes practically instantaneously with terric force. This force acting against the bullets 2l drives them back against -`their powder charges 20 with suiiicient impact to explode the charges. Furthermore, although .the powder charges 2D may be of conventional when exploded in accordance with the present invention, ordinary powders detonate rather than explode in the usual manner.

, It may not be necessary in all instances to loop fthe element 23 into the muzzle of each gun bore cause the gun body must usually be made of high quality tool steel which is expensive, in addition to being relatively diiicult to machine. High quality steel is desirable, if not essential, in order to secure the necessary strength to withstand the violent explosive forces that are employed and to reduce the wear of the gun bores from repeated use. Special steel known in the trade as Omega steel has been found satisfactory, although various other steels maybe equally suitable.

It may be desirable in some instances to distribute the different gun bores I9 in the cylindrical body of Fig. 1 so that different bullets are shot in diierent directions. There is shown in Fig. 6 a construction in which the different gun bores are arranged with their muzzles in a helical path extending around a cylindrical body Ib, in which case the groove 11b containing the detonating element is inthe form of a helix extending across the gun muzzles.

There is also shown in the detail view of Fig. 5 a different manner of providing additional quantities of the detonating element in the muzzle of each gun bore. Thus in the construction of Fig. 5, the main element Hic is extended straight across the gun muzzles but a short piece 21 of the explosive element is looped around the element IEc at each gun bore and the ends extended into the gun bore. The friction of the elements 2'I against the walls of the gun bores is relied upon to retain them in position.

In the arrangement of Fig, '7 additional explosive force 1s obtained by placing a capsule -as shown in Fig. 1. In some: instances the force Y fof the explosion of the element I6 is suiilcient to fdetonate the powder 2D if the element is simply extended straight across the muzzle. The exact lamount or length of the element that must be positioned in or adjacent to the muzzle is dependent upon the explosive properties of the ele- Kment, the length of the gun` bore, the tightness with which the bullet is tted in the gun bore, the flquantity and nature' of the sealing member 22 and the character ofthe powder charge 20, all of Qwhich factors may be varied to suit particular circumstances.

,Various commercial explosive elements can be femployed as the element IB, typical examples of gwhich are sold under the trade inames of Primacord, Mericalcord and Cordeau. An explosive that maybe used as the core of the element lli is penta erithritol tetranitrate, the speed of propagation of the wave front of which is, I believe, about 21,000'feet per second. 1 A great advantage of the construction described is the simplicity of the gun structure itseli It may be forged from a single billet of tool steel and the groove I1 -and the gun bores I9 f formed by simple conventional machining operations. wires, threads and seals-are required other than the seal necessary to protect the powder charge from uids that may be present. f', `When the gun barrels or bores are all posi- "tioned in a single vertical plane, the cross section of the gun body need not necessarily be circular as shown in Fig. 3; Instead it might be rectangular as shown at Illa in Fig. 4, in which It is to be particularly observed that no 3u of fluid-resistant, yieidable material within `the gun bore in iront of the bullet 2id, the capsuie containing a suitable explosive.

In any of the arrangements shown in the drawing, the force applied to the bulletvmay be increased by applying a gob of quick drying cement over each muzzle as the nal operation. The cement acts as stemming to increase the force of the explosion in the opposite direction, that is, into the muzzle.

An alternative arrangement of the gun barrels to those disclosed in Figs. 1 `and 2 is to arrange them all in a single vertical plane but have successive barrels pointing in opposite directions so that the recoil forces are more or less balanced. Such a gun may be of circular cross section as shown in Fig. 3 or of rectangular cross section as shown in Fig. 4. Detonation may be eiected by employing two separate elements I6 in two grooves corresponding to the grooves II positioned on opposite sides of the body or a single explosive element positioned in a he-ical groove extending across all the gun muzzes may be employed as shown in Fig. 6.

Although the adapter Il may be secured to the body I0 in various manners, a particularly effective way is to employ a snap ring 3| which normally expands to completely ll a shallow groove 32 in thebody and extend in the groove 33 in said adaptor II. The ends of the ring are bent out into a recess 34 in the body and by squeezing the ends of the ring together, the ring can be collapsed completely within the groove 33 to permit release of the adapter from the body I0. A rubber washer 41 is provided between the lower end of the adapter and the case some material caribe saved and a turning body to reduce leakage of current from the lbanana contact I2a and jack I2b to the body Iin the presence of conductive fluids.

The use of the removable fuse tube |5a permits rapid reloading ofthe gun in the field, since a number of extra tubes having fuses cemented aandoet therein may be kept on nana. nach ruse may 'be connected to its tube by a Ysoldered lead to complete the circuit to ground.

'The explosive cord Ilr may, insome instances, advantageously lconsist of metallic tubing such a's lead or copper, iilled Vwith Aan explosive hav'-` ing Vthe necessary characteristics. The metal will resist the action of the fluids .present in some wells better 'than the impregnated fabric `coverings 'comrrior'ily used on such fuse structures.

If desired, separate gun `barrels 'may be vernployed as shown in Fig. 8 in which barrels 36 are l'freely tted in sockets f31 provided therefor in the body 10e 'and detachably retained 4in place with snap rings 38 functioning the same as the snap ring 31 of the adapter ifi. The use of 'the separate gun barrels :facilitates 'reloading ofthe 'gun iin the A.held since a 'supply of loaded 'barrels may be carried along. -rrhis manner of securing barrels in their sockets is ydisclosed in my copending application VSerial No. 527,110, now Patent No. 2,402,153, granted June 1K8, 14946.

There 'is disclosed in Fig. 9 an alternative vmethod of driving the bullet back to explode the main charge. `In this embodiment, 'a charge of explosive 41) is placed in the bore l9f in front of the into a shallow counterbore at muzzle rend of jborc I9. To explode -the charges 30 a longitudinal hole 42 intersecting the'bores 19j may be provided and the lhole yilled with powder 'which is ignited `by an Aelectrical fuse l5]rc at the upper end. To limit dissipation into ythe hole 42 of pressure developed in the `gun bores 191, screw 'plugs B4 vhaving small transverse vpassages l5 lthereinmay be screwed into tapped holes Vprovided ltherefor irnmediately y.above and below each gun bore I'9', which plugs canbe replaced when their passages 45 have 'been eroded by use.

When -'the system of Fig 9 is used, the explosive maybe any oneof .many known types. One that is suitable .is `a double base .pistol powder such as the y.product of -the Hercules :Powder Co. known vin the trade as fBulls Eye brand.

rllt will 'be observed from the `foregoing descr-ip- -tion of 'several {for-ms which the Ninvention may assume, that in each vinstance vthe propulsive charge -20 is `detonated by the concussion or detonation force of `detonation means disposed in front of Athe bullet, the vdetonation .force of which is transmitted to the -propulsive charge bythe bullet. This novel firing method and arrangement possesses vseveral distinct advantages over otherknown firing .methods and arrangements. The :gun structure is thereby .rendered `simpler and less costly to manufacture, since the gun bores .are open only at one end and no `auxiliary passages are required to afford access to the powder chamber rearwardly of the bullet. Furthermore, the elimination of such other passages simpliiies the problem `of `sealing the powder chamber from the 4fluid in which the gun lis usually immersed when iired.

Another important aspect of this invention relates to the `greatlyincreased Vpropellent effect of the ,powder charge when detonated by this method. 'I have discovered .that certain explosives of the propulsive type, such as that sold under the vtrade 'name "-B-ulls Eye, are in fact what may be termed self-detonating concussion responsive explosives which can vbe detonated-by concussion alone, without the faid of Vprimers 'or detonation initiators. Furthermore, I have found that when such an explosive is detonated in this manner its propellent effect is greatly enhanced.

t This `increased propellent effect'is of utmost ,im-l portance in gun perforating of well casing, .for obvious reasons. The gun bores of gun .perforators are necessarily relatively short, and, Yin order to impart the necessary muzzle velocity to the bullets, various expedients have .heretofore been resorted to, such as the provision oi frangible disks or the like to retard movement Y of the bullets until 'the l.pressure developed by bullet and sealed against fluid lby a disk 4| `pressed the explosion of the propulsive charges reaches a predetermined magnitude. I-have found, however, that by firing in accordance withmym'ethod a very high muzzle velocity is attained without the use of such retarding devices. It is 'selfevident that when -a retarding device such as `a frangible disk is employed, a substantial portion of the energy developed by the 4explosive is vconsumed in shearing the disk, and for this reason such devices iat least partially defeat their own purpose. The attainment of sufficient muzzle Vvelocity by the vmannerof detonatin'g the propulsive charge, in contradistinction -to the ruse of retarding devices, is therefore considered -to be a great forward step in this far-t.

Another factor contributing to the 'increased muzzle velocity is the fact tha-t the pressure wave from the detonation of the explosive charge in front Yoi the bullet is eiective 4to momentarily 'retard the outward movement of *the y'lflulletand thus allow the pressure behind the `bullet -to rise to a relatively high value before the bullet starts to move. The peak of vthe pressure wave in front of the bullet is reached substantially simultaneously with the initiation ofthe lexplosion in back of the bullet, and, as the pressure 'behind the bullet increases, the pressure in iront of the 'bullet decreases. The bullet obviously-cannot move forwardly until the pressure behind the Ybullet lex'- ceeds that in iront of the bullet, and when this condition prevails the pressure "behind the bullet has reached a high value. The pressure infront of the bullet decreases very 'rapidly Ydue to the rapid cooling of the gases by the surrounding liquid, and consequently bythe time 'the Vbullet has moved a 'very short distance the pressure wave in front 'thereof has vsubsided to 'substantially the hydrostatic pressure of the liquid.

Still another factor which contributes to increased muzzle velocity and greater penetrating effect of the bullets is the fact lthat asthe Vbullet moves forwardly the path of the bullet is filled with gas from the detonation of the charge in front of the bullet. Ordinarily, when a gun perforator is red by other known methods, the bul'- lets are projected through a body of liquid, which obviously offers more resistance 'than a body 0i" gas. Consequently, by this method of firing there .is materially less decrease .in velocity of the 'bul'- let between its emergence from-the gun bore and its contact with thecas'ing.

Although an important yphase of this invention relates to the detonation of the propulsive charge by the rearward concussion transmitted thereto vby the bullet from the detonation of an explosive charge in front oi the bullet, it will be apprecr- ,ated that the advantages resulting from this method of ring are attained even though .detonation of the propulsiva charge by concussion may be `assisted oraugmented'by the use of priming means. Hence `it is to be understood .that priming means may be used, if desired, and the terms propulsive charge and explosive meansf as used in the appended claims, do not necessarily exclude priming means associated with the powder charge.

Although for the purpose of explaining the invention certain specific embodiments thereof have been described in considerable detail, many changes from the exact construction shown may be made without departing from the invention which is limited only to the extent set forth in the appended claims.

I claim:

1. A gun perforator, comprising: a gun body structure dening a plurality of laterally directed gun bores; bullets in said gun bores; concussion responsive explosive means in said gun bores rearwardly of said bullets; and fuse-like detonation means passing along said gun bodyand traversing the muzzle ends of said gun bores.

2. A gun perforator as set forth in claim l, in which said gun body structure is provided with an external groove intersecting the muzzle ends of said gun bores and adapted to receive said fuse-like detonation means.

3. A gun perforator comprising: a gun body structure denng a plurality of laterally directed gun bores angularly disposed with respect to each other; bullets in said gun bores; concussion responsive explosive means in said gun bores rearwardly of said bullets; and fuse-like detonation means wrapped helcally about said gun body structure and traversing the muzzle end of each of said gun bores.

4. A gun perforator as set forth in claim 3, in which said gun body structure is provided with a helical groove intersecting the muzzle ends of said gun bores and adapted to receive said fuselike detonation means.

5. A gun perforator comprising: a gun body structure deiining a plurality of laterally directed gun bores; bullets in said gun bores; concussion responsive explosive means in said bores rearwardly of said bullets; detonation means in said bores in front of said bullets; and common means for detonating all of said detonation means.

6. A gun perforator comprising: a gun body structure defining a plurality of laterally directed gun bores; bullets in said bores; concussion responsive explosive means in said bores rearward- A ly of said bullets; irst detonation means in said bores in front of said bullets; and fuse-like detonation means passing along said gun body structure in detonating relation to each of said first detonation means.

'7. A gun perforator comprising: a gun body vstructure deiining a plurality of gun bores; bullets in said gun bores; concussion responsive explosive means in said gun bores rearwardly of said bullets; walls dening a passage within said gun body structure and communicating with each of said gun bores; detonation initiating means in said passage; and detonation means in each of said gun bores in front of the bullets in position to be detonated by said detonation initiating means.

8. The method of discharging projectiles from the gun bores of a gun perforator, which comprises: exploding primary detonation means in close proximity to the muzzle ends of said gun bores; exploding secondary detonation means in said gun bores in front of the projectiles by the force of said primary detonation means; transmitting by the projectiles the force of said detonation means to concussio-n responsive explosive means in said gun bores rearwardly of said projectiles; and detonating said concussion responsive explosive means by said transmitted force to discharge the projectiles from the gun bores.

9. A'well casing perforating gun comprising: a body having a plurality of firing barrels therein', each barrel Abeing adapted to be loaded with a projectile, a propelling charge between the projectile and the closed rear end of the barrel, and a priming charge between the projectile and the discharge end of the barrel, and common igniting means associated with the respective discharge ends of the barrels andadapted to cooperate with the several priming charges in exploding the latter so as to drive 'the 'respective projectiles rearwardly, compressing therpropelf ling charges to a point where the latter' are ex`l ploded so as to drive the projectiles from thebar-` Tels. v

10. A perforating gun as defined in the preceding claim wherein the discharge ends of the barrels are arranged in helical formation around the body andthebody is provided with a helical groove associated with said dischargejends and adapted to receive said common igniting means.

11. A gun having barrels adapted for the use of loads each consisting of a projectile, a propelling charge adjacent the rear end of the projectile, a priming charge adjacent the front end of the projectile adapted to be fired by a priming cord, and a closure to seal the front end of the barrel, comprising: a gun body having a plurality "of gun barrels extending thereinto from the exterior to receive said loads, and a passage in sald body to receive said priming cord, communieating with the portions of said barrels which receive said priming charges; and means for igniting said priming cord.

12. In a gun wherein a propelling charge adjacent therear end of a projectile is ignited by driving the projectile rearwardly in the gun barrel: a gun body having a plurality of barrels leading in from the exterior thereofand a priming cord passage extending within the body, said priming cord passage communicating with the portions of said barrels between the outer endsY of the projectiles and the outer ends of the barrels.

13. In a gun wherein a propelling charge adjacent the rear end of a projectile is ignited by driving the projectile rearwardly in the gun bar rel: a gun body having a""plurality of barrels leading in from the exterior thereof and a priming cord passage extending within the body, said priming cord passage communicating with the portions of said barrels between the outer ends of the projectiles and the outer ends of the barrels; and means to close the outer ends of said barrels. A

14. A gunY perforatoncomprising: a gun body structure deining a gun bore; a bullet slidable rearwardly in said gun bore; Yconcussion responsive explosive means in said gun bore in back of said bullet, and a primer cell in said gun bore in front of said bullet, said primer cell including a wall engageable with the nose oi said bullet and a second wall cooperating with said front wall to form a chamber f or an explosive.V

RAYMOND D. ELLIOTT.

REFERENCES' CITED' The following references-are ofrrecord lthe iile of this patent:

UNITED STATES PATENTS Wells Apr. 21,y 1936 

